libgo/go/hash/crc32/example_test.go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package crc32_test

import (
	"fmt"
	"hash/crc32"
)

func ExampleMakeTable() {
	// In this package, the CRC polynomial is represented in reversed notation,
	// or LSB-first representation.
	//
	// LSB-first representation is a hexadecimal number with n bits, in which the
	// most significant bit represents the coefficient of x⁰ and the least significant
	// bit represents the coefficient of xⁿ⁻¹ (the coefficient for xⁿ is implicit).
	//
	// For example, CRC32-Q, as defined by the following polynomial,
	//	x³²+ x³¹+ x²⁴+ x²²+ x¹⁶+ x¹⁴+ x⁸+ x⁷+ x⁵+ x³+ x¹+ x⁰
	// has the reversed notation 0b11010101100000101000001010000001, so the value
	// that should be passed to MakeTable is 0xD5828281.
	crc32q := crc32.MakeTable(0xD5828281)
	fmt.Printf("%08x\n", crc32.Checksum([]byte("Hello world"), crc32q))
	// Output:
	// 2964d064
}